Gas lasers in which lasing action of the gas molecules is induced by pulsed electromagnetic field are well-known. High energy gas lasers are designed to circulate a gas, such as helium, neon, argon, or krypton continuously through a lasing chamber or cavity at subsonic velocities. Lasing action is produced in the cavity by applying a pulsed electromagnetic field across the cavity in a direction perpendicular to the axis of flow of the gas. Excitation of the gas molecules produces electromagnetic radiation at frequencies characteristic of the particular gas being used. Mirrors on either side of the cavity direct the radiation out of the cavity along an axis mutually perpendicular to the axis of the gas flow and the axis of the electric field.
To provide a uniform wave front of the light emitted from the cavity, it is necessary that the gas density be as uniform as possible throughout the lasing cavity. However, when the cavity is pulsed to induce lasing action in the gas, shock waves are generated which are transmitted through the gas. These shock waves tend to disturb the uniform distribution of gas molecules in the gas upstream of the laser cavity. While baffle systems have heretofore been used to absorb energy from the shock waves, a certain amount of time is required for the gas flow to return to a uniform density within the laser cavity before the electromagnetic field is again pulsed, thus substantially limiting the frequency with which the laser can be pulsed.